Therapeutic target studies using experimental disease models are complicated by the dynamic nature of RNA mis-splicing in MDS: mouse models of SF3B1 mutation develop anemia but feature distinct RNA splicing from humans [20–22]; primary patient material is heterogeneous, has limited availability and in vitro longevity; and cell models do not fully recapitulate the complex splicing repertoire. This evidence concerns the gene SF3B1 and anemia (phenotype).